I have a sleepnumber... I forget which model number it is, but it has the smallest amount of pillow top possible. Mine is a "split king" and I have the adjustable base. My one complaint is since it is a "split king" sometimes the two beds slide apart. The bed is really comfortable, its great to sleep with your feet elevated if you've had a long day, and during cold season elevating your head is great for when you have a stuffy nose. The massage feature does nothing for me, but I guess would be fun to impress chicks with.
They say they will last 20 years. My understanding is that the warranty is 20 years. First 2 years, everything is covered 100%. After that, you have to pay a little bit. We've had ours for over 2 years.